Have you ever thought about why the twins are alike? After all, it can not be not interesting to those who are interested in medicine or just interesting facts about a person.
Twins - This is an exception to the rules. They have the same set of genes, because they evolved from one fertilized egg cell, which was divided in half, and each of its halves became a separate organism.
Such twins are called identical (monozygous).
But there are also many multiple (heterozygous or dyzygotic) twins. They are born if two eggs are fertilized at once. The set of genes in these twins is not the same, so they may be of different sexes and not at all resemble each other.
You may also be interested in an article about what chromosomes are and how they affect the fact that in one family all of the other are similar to each other.
The mystery of the twins is not fully solved until now. As far as they are physically and spiritually connected, why do they feel each other even at a great distance? - all this scientists have yet to study.